1. Field of the Invention
The present invention relates to a socket contact. In particular, the present invention relates to a socket contact that is elastically connected to a counterpart contact shaped like a flat plate and that can be mounted to a printed board.
2. Related Art
In recent years, a small motor is installed inside an imaging electronic device. Generally, such a small motor has a pair of flat plate-like contacts (hereinafter referred to as input terminals). Power is supplied to these input terminals so as to activate the small motor.
For example, the input terminals of the small motor described above are directly connected to ends of electric wires by soldering. In addition, the input terminals are soldered in through holes, which are provided in a rigid or flexible board. A compact imaging electronic device frequently uses a flexible board that is structurally divided into multiple branches and foldable. This flexible board provides electrical connection between the small motor, internal electric and electronic elements, and the like.
It is difficult to introduce automation into a process in which an input terminal of a small motor is soldered to a flexible board. The reason for this is that since the automated process requires the flexible board and the input terminal, accordingly including the small motor, to be placed in a reflow furnace so as to perform automatic soldering, the process has an adverse effect of heating on the small motor. As a result, it has been necessary to rely on manual operation by a skilled worker instead. This has hindered improvement in productivity.
Under the circumstance as described above, a small motor has been disclosed, having features such as a mechanism of easily detachable attachment to a flexible board, versatility and a possible reduction in cost (see Patent Document 1 for example).
Patent Document 1: Japanese Unexamined Patent Application Publication No. Hei 5-115148
FIG. 23 is a perspective exploded view illustrating the main part of a small motor according to Patent Document 1. In FIG. 23, a small motor 80 has a case 81 shaped like a hollow cylinder having a bottom. The case 81 internally includes a rotor including an armature and a commutator (not shown). An insulating end plate 82 is attached to a rear end of the case 81.
In FIG. 23, an end of a pair of brush arms (not shown) electrically connected with the commutator in a slidable manner protrudes from the end plate 82 as an input terminal 83. A circular cylinder-like bearing portion 84 for rotatably supporting an end of the rotor protrudes from the end plate 82. At an outer circumference of the bearing portion 84, a circular ring-like protrusion 84a rises.
As shown in FIG. 23, a connector unit 90 includes a substantially circular disc-like housing 91 and a pair of strip-like contacts 92. Each contact 92 is fixed to the housing 91 and is shaped like a substantially circular arc. The housing 91 includes an opening 91a into which a printed board (not shown) can be inserted. In addition, at a center of the housing 91, there is a circular hole 91b engaging with the bearing portion 84. At both sides of the hole 91b, a pair of rectangular insertion holes 91c is provided.
In FIG. 23, the contact 92 has a slit member 92a at a first end that is bent and inserted into an engagement hole (not shown) communicating with the opening 91a, and has a contact member 92c at a second end that is bent and inserted into the insertion hole 91c. When the connector unit 90, the housing 91 of which is assembled with the pair of contacts 92, is attached to the end plate 82, the electric continuity between the contact 92 and the input terminal 83 is established. Furthermore, when a printed board is inserted into the opening 91a, an end of the printed board is held between the slits of the slit members 92a. In this way, the electric continuity between the printed board and the contact 92 is established.
Patent Document 1 describes that it is possible to securely attach the printed board to the small motor only if one end of the printed board, Flexible Printed Circuit (FPC), for example, is inserted into the connector unit which has been attached to the end plate of the small motor. Furthermore, Patent Document 1 describes that since the printed board, which is detachably attached to the connector unit, can be easily adapted to different circuit requirements, it reduces a burden associated with the maintenance performed by a user, such as a manufacturer of assembled products.
However, electronic devices that are compactly configured in recent years internally include densely mounted elements. Therefore, such electronic devices have no room for mounting a contact, which has a housing as described in Patent Document 1, to a small motor. It has been difficult for the manufacturer to accept such a contact. Accordingly, there is a demand for a socket contact of a different type, which has the following features: Bare contacts, which are not supported by a housing, are mounted on a printed board such that the socket contact has a height (a height for being mounted) small enough when it is connected to an input terminal of a small motor.
In addition, in order to connect the socket contact to the input terminal of the small motor with low electric contact resistance, the input terminal is preferably subjected to gold plating. However, such gold plating is not generally adopted in order to reduce the manufacturing cost of the small motor. Instead, a bare surface is common, and a surface treatment more than zinc plating or tin plating is not adopted. For these reasons, a socket contact that has a mechanism for increasing a contact pressure has been required such that an electric contact resistance can be restricted to a certain low value.
Furthermore, it is preferable that the socket contact is structurally configured to be easily manufactured in an automatic assembly line when it is mounted onto a printed board. Such structure of the socket contact can improve productivity. It is one of objectives of the present invention to solve the above-described disadvantages.